1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.
Note that the semiconductor device in this specification refers to all devices that can function by utilizing semiconductor characteristics, and electro-optic devices, semiconductor circuits, and electronic appliances are all semiconductor devices.
2. Description of the Related Art
A technique by which transistors are formed using semiconductor thin films formed over a substrate having an insulating surface has been attracting attention. The transistors are applied to a wide range of semiconductor devices such as an integrated circuit (IC) and an image display device (also simply referred to as display device). A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, a transistor including a semiconductor layer formed of an amorphous oxide containing indium (In), gallium (Ga), and zinc (Zn) (an IGZO-based amorphous oxide) is disclosed (see Patent Document 1).